By a load-carrying vehicle is meant in particular trucks and their trailers, as well as buses. The load-carrying vehicle always has a cargo space structure, which contains the goods or persons intended for the transport. The cargo space structure is bounded by fully or partly enclosed side walls and a roof wall. During rapid forward travel of the load-carrying vehicle, a negative pressure arises in the region behind the cargo space structure, resulting in a suction effect and increasing the fuel consumption of the load-carrying vehicle.
In the prior art there have been many attempts to lengthen the contour of the tail by means of a cone formed on it, so that the air flowing across the cargo space structure lies against the cone and thereby reduces the suction effect. Thus, US 2011/0068603 A1 proposes placing a tubular bulge at the rear of the load-carrying vehicle, which almost entirely surrounds the contour of the cargo space structure in the circumferential direction.
U.S. Pat. No. 8,360,509 B2, on the other hand, discloses the use of foldable wall elements in place of a tubular bulge, while US 2007/0001481 A1 proposes an enclosed cone which is telescopic in the axial direction.
What all these devices have in common is that the air conducting surfaces forming the cone are arranged solely behind the cargo space structure so as not to further increase the coefficient of air resistance.
The major drawback of these rear-side air conducting surfaces is that the cargo space structure can only be unloaded with major expense, since its rear doors can only be opened after a prior disassembly of the air conducting surfaces. Furthermore, on account of the rear-side mounting of the air conducting surfaces, the permissible vehicle length is significantly exceeded, so that it is necessary to shorten the effectively usable cargo space structure.
EP 1 860 023 A2 proposes taking up the air flow across the cargo space structure during travel by means of a rigid-shape, tubular structure and channeling it to the negative pressure region located behind the tail. However, the tubular structure has proven to be a drawback, since it results in greater height of the vehicle, which may result in contact with the roof of the cargo terminal during maneuvering at roofed cargo terminals and corresponding damage to both the roof and the tubular structure. The height of the tubular structure cannot be seen from the driver's cabin on account of being mounted at the rear and at the top side of the cargo space structure and therefore it is difficult to estimate it.
Based on these problems, U.S. Pat. No. 7,862,102 B1 discloses a device for reducing the air resistance in which extensible air conduction elements are arranged at the rear of a cargo space structure, which are swiveled by a rotational movement from a starting retracted position to an extended travel position. However, it has found to be a drawback that the dimensions of the load-carrying vehicle are increased during the execution of the rotational movement beyond the level in the starting and travel position, which leads to problems with the legal regulations and furthermore increases the risk of collision with bridges and other road users during the swiveling movement of the air conduction elements.
For this reason, the problem which is invention proposes to solve was to develop an air conduction element with which the maximum vehicle dimensions defined by its travel position are also maintained during the adjustment.